Spark plug



VIII!!! f i INVENTOR foy 7T' fwufy 2241114 dm ATTORNEYS sept 9, 1930.

Patented Sept. 9, 1930 i UNITED STATES PATENT oFFlcE ROY T. HURLEY, F DOBBS FERRY, NEW YORK SPARK :PLUG

Application led August 5, 1927. Serial No. 210,895.

This invention relates to spark plugs, and as indicated by numeral 14, to provide a seat has for its object the provision of means for for a tapered i'errule 15, formed of soit metal. effecting a sealing joint between the cen- The invention is applied in the following ter electrode and the insulator. manner: the ferrule 15 is placed in position The following is. a description of a spark upon the'fluted shoulder portion 7 of the cen- 155 plug sealing joint embodying the invention ter electrode 6, as shown in Fig. 2, the upper in the form at present preferred; but it will portion of the ferrule being seated in the be understood that various modilications chamfered recess 14 of terminal post 8. A and changes may bc. made without departing quantity of cement, 12, in a plastic state, is

1G from the spirit of the invention and without then introduce into the bore of the insulator 60 exceeding the scope of the claims. 4, in accordance with the usual custom in this The invention will best be understood by art. The assembly as shown in Fig. 2 is then reference to the accompanying drawings, inserted in the bore of the insulator, and wherein Fig. 1 is a view, partly in vertical pressure is applied between the terminal post 15 section and partly in elevation, of a spark portion of such assembly and the lov-7er end 65 plug to which the invention is applied; Fig. of the insulator. This pressure forces the 2 is an elevation of the spark plug terminal small lower end of tapered ferrule 15 into p-ost and center electrode. assembly to which the lower portion of the insulator bore, simulthe invention is applied-the ferrule which taneously forces the upper end of the lorrule embodies the invention being shown in secinto the chamfered recess 14 of the terminal 70 tion; and F ig. 3 is an elevation of said ferpost, and upsets or expands the portion of rule. the ferrule intermediate the chamfered re- Like referencel characters indicate like cess and the shoulder 18 formed in the insuparts throughout the drawings. lator. As a. result, the lower end of the fer- Reierringtothe drawings, 1 isa shell which rule is tightly wedged into the small diam- 75 maybe of conventional type, attached to the eter portion of the yinsulator bore; the uplower end of which is ground electrode 2. setting' of the upper portion or' the ferrule rlhe bore of the shell is provided with a shoulforms a shoulder thereon which is tightly der forming a seat for a gasket 3, comprising pressed against the shoulder 18 formed in a sealing joint between said shell and a shoulthe insulator; and the extreme upper end of 80 dered portion of an insulator 4. The insuthe ferrule is seated in intimate contact with lator is also provided with an upper shoulthe wall of the chamfered recess 14 in the-- dered portion forming a seat for gasket 5, terminal post. It will be understood that which, through pressure applied by means the plastic cement 12 enters the flutes 7 and of threaded coupling-nut 17, effects asealing 9 and also iills the annular recess between 85 joint in the upper portion of the plug. A the shoulder 18 and the upper wall of the recenter electrode 6 is ositioned in the bore of cess formed in the terminal post flange 1G. It the insulator, such e ectrode being provided will be obvious that the upsetting or expandnear its upper end with a fluted shoulder poring, by pressure, of the upper portion of the tion 7. The extreme upper end of the center ferrule causes pressure` upon the surrounding 90 electrode is adapted to be seated in a recess plastic cement, thus insuringr an intimate con- 13 formed in the lower end of a terminal post, tact thereof with said ferrule.

8. The lower portion of the periphery of the Following the hereinbei'ore described proterminal post is provided with flutes 9; and cesses, heat is applied to the insulator and its the upper end of said post is provided with associated parts, causing the cement to har- 95 the usual screw-threads 11 for receiving a den and effecting a firm b'ond between the vaterminal nut (not shown). Near its vertical rious elements. The entire spark plug is then center, the said terminal post is provided with assembled in the usual manner.

an annular recessed flange 10. The extreme The wedging of the ferrule into place, in

lower end of the terminal post is chamfered, conjunction with the adhesive action of the cement, insures a very efficient sealing joint between the center electrode and the insulator. Furthermore, it is, of course, desirable that in the nished spark plug the electrode 6 shall be centrally disposed with reference to the bore of the insulator. The tapered ferrule contributes to this end by reason of the fact that, in assembling the parts in the manner described, it serves as a pilot to centralize the electrode 6. As shown, a slight space is left between the cement 12 and the lower por tion of the electrode 6 for the purpose of permitting expansion of this portion of the electrode.

I claim: Y-

1. In a spark plug, the combination of an insulator, a center electrode, a soft metal ferrule for eiecting a sealing joint therebetween and cement surrounding said errule and said electrode.

2. In a spark plug, the combination of an' insulator provided with a bore of two diameters and a shoulder therebetween, a center electrode adapted to enter said bore and having a. shoulder thereon and a ferrule constructed and arranged to enter the small diameter bore of said insulator and "tofbe upset between the electrode shoulder 'and the into the space between th/e electrode and the signature to this specification.

ROY T. IIURLEY.

shoulder of the bore in order to effect a sealf ing joint between said insulator and said electrode. v

3. In a spark plug, the combination vof an l insulator provided with-a bore of two diameters and a shoulder therebetween, a center electrode adapted to enter said bore and a terminal post provided with a chamfered recess, and a ferrule constructed and arranged to be upset between said shoulder and said recess in order to eect a sealing joint between said insulator and said electrode.

4. In a spark plug, the combination of an insulator provided with a bore of two diameters and a shoulder therebetween, a center electrode adapted to enter said bore and a terminal-post provided with a chamfered recess, and a ferrule constructed and arranged to enter the small diameter bore of said insulator and to be upset between said l shoulder and said chamfered recess in order to eiect a sealing joint between said insulator and said electrode.

5. In a spark plug, the combination of an insulator, a center electrode, a soft metal fer-V rule for eecting asealing joint therebe-l tween, said center electrode being fluted at the region of said ferrule and said electrode and cement surrounding said :terrule and said electrode, y

6. In a spark plug, the combination of a.

center electrode, an insulator having a bore at least a portion of )which iso larger Ydiameter than requiredfor tting purposes with respect to said electrode, said electrode having a shoulder and a errule disposed below said shoulder and adapted to be wedged 

